The invention relates to an apparatus for needling a non-woven material with a support for at least one needleboard with at least two eccentric drives which are drivably connected with the support via connecting rods and with a device for adjusting the mutual angular position of the two eccentric drives.
For the purpose of the reciprocating drive of a needleboard not only in the direction of the needle penetration but also in the direction of the advance of the non-woven material it is known in needling apparatuses (EP 0 892 102 A2) to provide, in addition to the two eccentric drives which are drivable in opposite directions, two additional eccentric drives which are drivable in opposite directions for the needleboard drive in the needle penetration direction and whose connecting rods are connected by a coupling linked to a support for the needleboard. As a result of a respective choice of the mutual angular position of the two eccentric drives it is possible to set the throw of the needleboard advance in the direction of passage of the non-woven material. For this purpose the two eccentric drives are driven by separate motors which are driven via a control device according to a predetermined mutual angular position, which entails considerable efforts regarding the drive and the control systems.
The invention is thus based on the object of providing an apparatus for needling a non-woven material of the kind mentioned above in such a way that the mutual angular position of the two eccentric drives for setting the drive conditions for the needleboard support, which drive conditions can be determined by said eccentric drives, can be set in a simple manner with a low amount of control efforts also while the needleboard is driven.
This object is achieved by the invention in such a way that the device for adjusting the mutual angular position of the two eccentric drives consists of a superposition gear in a gear train for the drive connection of the two eccentric drives.
In a superposition gear, the basic gear ratio given between a drive member and a driven member can be changed via an additional drive member because the speed of the driven member is determined by the superposition of the speeds of the two drive members. If the additional drive member is held against rotation, the basic gear ratio is obtained which can be utilized for the synchronous drive connection of the two eccentric drives. The angular position between the drive member and the driven member is adjusted via an adjustment of the angle of rotation of the additional drive member, which leads to the setting of a random angular position of the two eccentric drives if it is ensured that the entire gear ratio of the gear train connecting the two eccentric drives is 1. This can be ensured in a simple way such that the superposition gear shows a basic gear ratio of 1.
Since the eccentric drives which are to be set concerning their mutual angular position comprise parallel eccentric shafts, it is recommended to connect the superposition gear via angular gears with the eccentric drives in order to create simple constructional conditions for the gear train between the two eccentric drives.
Although the use in accordance with the invention of proven superposition gears for setting the motion stroke of needleboard drives with separate eccentric drives for the needleboard movement in the needle penetration direction and the direction of advance of the non-woven material can be utilized advantageously, particularly advantageous constructional conditions can be obtained when the connecting rods of the two opppositely drivable eccentric drives for the needleboard drive in the needle penetration direction do not comprise a middle position conventionally extending in the needle penetration direction, but extend in an opposite inclined manner with respect to the needle penetration direction, so that as a result of the phase shift between said two eccentric drives the support for the needleboard can be driven along an inherently closed trajectory which allows an advantageous adjustment of the needle movement to the advance of the non-woven material when the support is guided parallel with respect to itself, which can be ensured by a hinged parallelogram guidance of the support via at least one additional eccentric drive. Since with the phase shifting between the two eccentric drives it is not only possible to set the throw of the needleboard advance in the direction of passage of the non-woven material but also in the needle penetration direction, the additional advantageous possibility is obtained to structure the non-woven material by changing the needle penetration depth of the needles in the non-woven material during the needling process and to thus provide the material with a pattern. The change of the needle penetration depth can be made within a few needleboard strokes.